1. Field of the Invention
This invention is in the field of wood-type golf clubs having an insert in the striking face thereof, the insert being composed of a high yield strength metal and being configured such that the front face of the insert is capable of elastic flexing.
2. Description of the Prior Art
The patented prior art contains numerous disclosures of various materials suitable for use as inserts in the striking face of a wood golf club. U.S. Pat. No. 699,624 to Kempshall describes a wood golf club having a facing composed of celluloid and a fabric, the celluloid being impregnated into the fabric. The theory of this patent was that the celluloid was sufficiently hard not to be pitted or injured by impact of the ball and yet was elastic.
Thompson et al. U.S. Pat. No. 838,284 described a golf club in which the head was formed of a metal casting which was filled with a resilient material such as rubber, the striking face of the head being cut away to expose the rubber filler.
Beamer U.S. Pat. No. 1,359,220 described a golf club having a metallic striking plate fitted into a recess in the club face and wall portions extending rearwardly from the edges of the face, the plate being spaced from the rear wall of the depression so that it is free to vibrate.
Farrington U.S. Pat. No. 2,040,252 described an insert for a wood-type club using a perforated plate in combination with a metal abutment behind the plate which was received within a recess.
Baker et al. U.S. Pat. No. 3,172,667 assigned to a predecessor of the assignee of the present application described a golf club head which eliminated the need for screws on the striking face. This patent described a club in which the face inserts were molded in place, the inserts consisting of synthetic resins such as epoxy, polyester or polyamide resins.
Burr U.S. Pat. No. 3,218,072 described a golf club which had impact receiving faces formed of blocks or inserts composed of hard, porous carbon. These inserts were said to have relatively high resilience per unit of volume and appreciable compressibility under moderate stress. These characteristics made it possible to secure the inserts in the club head solely by the expansive thrust of the insert against the walls of the recesses in which they were placed, making adhesives or other securing devices unnecessary.
Flom U.S. Pat. No. 3,233,905 suggested a golf club having an impact face composed of a polycarbonate resin. Such inserts were said to exhibit dynamic losses over a wide range of temperatures which were much lower than those of other thermoplastic materials.
Lynn U.S. Pat. No. 3,567,228 suggested a golf club striking face which included an insert having a very high modulus of elasticity, typically on the order of 28,000,000 pounds per square inch, and more. The use of such high modulus metal inserts was said to minimize deflection thereby reducing the amount of energy which was capable of being absorbed and wasted within the club head.
Averbach U.S. Pat. No. 3,834,700 also taught the use of a high modulus insert and correlated this to a weight distribution such that the assembled golf club had a ratio of gross weight to swing weight which is less than 0.62.
Dance U.S. Pat. No. 3,836,153 described a golf club utilizing an insert composed of a molded piece prepared by curing a suspension polymerized polymethyl methacrylate powder containing a graft copolymer of butadiene and styrene in a liquid containing methyl methacrylate and glycol methacrylate as cross-linking monomers. The objective of this patent was to provide an insert which provided a better "click" and "feel" than in other plastic type inserts.
The prior art has thus disclosed many different types of insert materials for use in golf clubs, based upon varying considerations. The present invention is directed to an improved type of insert having a structural configuration which is different from the above prior art and provides an insert which is capable of elastic flexing and which can be manufactured and assembled more simply than other types of inserts.